Significant Accounting Policies - Comprehensive (Loss) Earnings Attributable to Martin Marietta Materials Incorporated (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Statement Of Income And Comprehensive Income [Abstract]
Net earnings attributable to Martin Marietta	$ 21.4	$ 65.3
Other comprehensive (loss) earnings, net of tax	(31.6)	2.8
(Loss) Earnings attributable to Martin Marietta Materials, Inc.	$ (10.2)	$ 68.1